Blur-calibration of an imaging sensor includes moving a known target pattern across the field-of view (FOV) of the imaging sensor to present the target pattern across different frames at different pixel phases. The known target pattern comprises a plurality of point-like objects with fixed relative positions in which at least one point-like object has a different focus position. Frames of images of the moving target pattern as seen in the FOV of the imaging sensor are captured to sample point-like objects at different focus positions and generate a multi-focal image data output, which may be subsequently processed to generate data products at different focus positions from a high-resolution composite image generated from the captured frames.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A system for blur-calibration of an imaging sensor, the system having an optical axis in a focus direction, the system comprising: a target having a known target pattern comprising a plurality of point-like objects with fixed relative positions, at least one said point-like object having a different focus position in the focus direction along the optical axis; a projection element to project at least a portion of the target pattern within a field-of-view (FOV) of the imaging sensor; a controller configured to move the target pattern across the FOV; and image-capture elements to capture frames of images of the moving target pattern as seen in the FOV of the imaging sensor to sample point-like objects at different focus positions and generate a multi-focal image data output, wherein the controller is configured to cause the target pattern to move across the FOV to present the target pattern across different frames at different pixel phases, wherein the multi-focal image data output from the image-capture elements is subsequently processed to generate data products at different focus positions from high-resolution composite images generated from the captured frames for the different focus positions.
2. The system of claim 1 , wherein said target has a fixed focus position within the test system.
3. The system of claim 2 , wherein said test system further comprises a focus adjustment capable of translating one of the target, projection element or imaging sensor to change the target's focus position, said focus adjustment left unchanged to generate the multi-focal image data output.
4. The system of claim 2 , wherein said target's fixed focus position is at the focus of the test system.
5. The system of claim 2 , wherein said target's fixed focus position is near the focus of the test system so that the point-like objects' different focus positions span the focus of the test system.
6. The system of claim 2 , wherein said target's fixed focus position is away from the focus of the test system so that the point-like objects' different focus positions do not span the focus of the test system.
7. The system of claim 1 , wherein said target comprises the known target pattern of said plurality of point-like objects with fixed relative positions in an x-y plane across the target surface with a constant position in a z direction perpendicular to the target surface, said target tilted with respect to the system's optical axis to create diversity in the positions of the point-like objects along the optical axis so that at least one said point-like object has a different focus position in the focus direction.
8. The system of claim 1 , wherein said target comprises the known target pattern of said plurality of point-like objects with fixed relative positions in an x-y plane across the target surface perpendicular to the optical axis, said target having a non-uniform surface relief in a z direction to create diversity in the positions of the point-like objects along the optical axis so that at least one said point-like object has a different focus position in the focus direction.
9. The system of claim 8 , wherein a substantial majority of the point-like objects have the same position in the z direction and same focus position and a few of the point-like objects have a different position in the z direction and different focus positions.
10. The system of claim 9 , wherein at least 60% of the point-like objects have the same position in the z direction and same focus position and less than 40% of the point-like objects have a different position in the z direction and different focus positions.
11. The system of claim 10 , wherein a data processor processes the high-resolution composite images generated from the substantial majority of point-like objects having the same focus position to generate data products representative of the relative coefficients of the even and odd terms of basis functions that describe an input wavefront associated with said point-like object and wherein the data processor processes the high-resolution composite images generated from the few point-like objects having different focus positions to determine the absolute sign of the even and odd terms.
12. The system of claim 1 , wherein a data processor processes the high-resolution composite images for the different focus positions to generate data products representative of absolute coefficients of the even and odd terms of basis functions that describe an input wavefront associated with said point-like objects across the FOV of the imaging sensor.
13. The system of claim 12 , wherein the data processor interpolates the absolute coefficients between different regions in the FOV to form a set of coefficients across the FOV, said data processor processing said set of coefficients to generate a point-spread function (PSF) across the FOV.
14. The system of claim 1 , wherein a data processor processes the high-resolution composite images for the different focus positions to generate data products representative of a shape of a point-spread function (PSF) for different focus positions.
15. The system of claim 1 , wherein a data processor processes the high-resolution composite images for the different focus positions to generate a through-focus curve.
16. A system for blur-calibration of an imaging sensor, the system having a system focus along an optical axis in a focus direction, the system comprising: a target positioned at the system focus and having a fixed focus position, said target having a known target pattern comprising a plurality of point-like objects with fixed relative positions, at least one said point-like object having a different focus position in the focus direction along the optical axis; a projection element to project at least a portion of the target pattern within a field-of-view (FOV) of the imaging sensor; a focus adjustment capable of translating at least one of the imaging sensor, target or projection element along the optical axis to change the focus position of the target, said focus adjustment left unchanged throughout the blur-calibration; a controller configured to move the target pattern across the FOV; and image-capture elements to capture frames of images of the moving target pattern as seen in the FOV of the imaging sensor to sample point-like objects at different focus positions and generate a multi-focal image data output, wherein the controller is configured to cause the target pattern to move across the FOV to present the target pattern across different frames at different pixel phases, wherein the multi-focal image data output from the image-capture elements is subsequently processed to generate data products at different focus positions from high-resolution composite images generated from the captured frames for the different focus positions.
17. The system of claim 16 , wherein said target comprises the known target pattern of said plurality of point-like objects with fixed relative positions in an x-y plane across the target surface position with a constant position in a z direction perpendicular to the target surface, said target tilted with respect to the system's optical axis to create diversity in the positions of the point-like objects along the optical axis so that at least one said point-like object has a different focus position in the focus direction.
18. The system of claim 16 , wherein said target comprises the known target pattern of said plurality of point-like objects with fixed relative positions in an x-y across the target surface plane perpendicular to the optical axis, said target having a non-uniform surface relief in a z direction to create diversity in the positions of the point-like objects along the optical axis so that at least one said point-like object has a different focus position in the focus direction.
19. The system of claim 18 , wherein a substantial majority of the point-like objects have the same position in the z direction and same focus position and a few of the point-like objects have a different position in the z direction and different focus positions.
20. A method for generating multi-focal image data output for use in blur-calibration of an imaging sensor, the method comprising: moving a known target pattern comprising a plurality of point-like objects with fixed relative positions, at least one said point-like object having a different focus position, across a field-of-view (FOV) of the imaging sensor to present the target pattern across different frames at different pixel phases; and capturing frames of images of the moving target pattern as seen in the FOV of the imaging sensor to sample point-like objects at different focus positions and generate a multi-focal image data output, wherein the multi-focal image data output is to be subsequently processed to generate data products at different focus positions from high-resolution composite images generated from the captured frames for the different focus positions.
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October 11, 2011
June 10, 2014
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